Signal seeking permeability tuner with automatically movable cores and manually movable coils



Dec. 23, 1958 J. c. H-ESELWOOD 2,866,095

SIGNAL SEEKING PERMEABILITY TUNER WITH AUTOMATICALLY MOVABLE CORE-S AND MANUALLY MOVABLE COILS 6 Sheets-Sheet 1 Filed Aug. 9, 1954 FIG. I.

INVENTOR.

JAMES CLE E MENT Y HESELWOOD ATTORNEYS Dec. 23, 1958 J. c. HESELWOOD 2,866,095

SIGNAL SEEKING PERMEABILITY TUNER WITH AUTOMATICALLY MOVABLE CORES AND MANUAL-LY MOVABLE COILS 6 Sheets-Sheet 2 Filed Aug. 9, 1954 INVENTOR. JAMES CLEMENT HESELWOOD ATTORNEYS Dec. 23, 1958 J. c. HESELWOOD 2,866,095

SIGNAL SEEKING PERMEABILITY TUNER WITH AUTOMATICALLY MOVABLE CORES AND MANUALLY MOVABLE COILS Filed Aug. 9, 1954 6 Sheets-Sheet 3 '6 f INVENTOR. FIG. 4. JAMES CLEMENT HESELWOOD ATTORNEYS 2,866,095 BILITY TUNER WITH AUTOMATICALLY ND MANUALLY MOVABLE COILS J. C. HESELWOOD SIGNAL. SEEKING PERMEIA Dec. 23, 1958 MOVABLE CORES A 6 Sheets-Sheet 4 Filed Aug. 9, 1954 mom ATTORNEYS Dec. 1958 J. c. HESELWOOD 2,866,095

E SIGNAL SEEKING PERMEABILITY TUNER WITH AUTOMATICALLY MOVABLE CORES AND MANUALLY MOVABLE cons Filed Aug. 9, 1954 I 6 SheetsSheet 5 FIG. IO.

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JAMES CLEMENT HESELWOOD ATTORNEYS Dec. 23, 1958 J. c. HESELWOOD 2,866,095

SIGNAL SEEKING PERMEABILITY TUNER WITH AUTOMATICALLY MOVABLE CORES AND MANUALLY MOVABLE COILS 6 Sheets-Sheet 6 Filed Aug. 9, 1954 www jmom D S R O n 0 O N we m W R E 1 W V F. T m 5 A H T m J m Y -n 9 8 E M A U m m N3 0mm *3 N 5;. 55 miu fibm zoo United States Patent i SIGNAL SEEKING PERMEAEILITY TUNER WITH AUTUMATICALLY 'MGVABLE CORES AND MANUALLY MOVABLE COILS James Ciement Heselwood, Havertown, Pa., assignor to Radio Condenser-Company, Camden, N. J., a corporation of New Jersey Application August 9, 1954, SerialrNo. 448,492

12 Claims. (Ci. ZED-40) This invention relates to radio tuners and has particular referenceto tuners in which tuning may be selectively effected in so-called signal seek fashion, by push button operation, or by manual knob tuning.

Heretofore there have been in widespread use automobile radio tuners of push button type in which :stations are selected through the manipulation of push buttons, the mechanism being preliminarily set up so that each push button corresponds to a particular transmitting frequency, the set up usually being made so that these frequencies correspond to those transmitting stations in the vicinity in which the automobile operator usually drives. an auto-mobile radio will depart from the vicinity of such stations, it is necessary additionally to provide a tuning knob by which the operator may tune in any station within the tuning band of the receiver.

Manual tuning by means of a knob necessarily requires some extended manipulation by a driver taking his attention from the road, and while the provision of push buttons makes for more ready accomplishment of tuning with a minimum of attention on the part of the driver, the fact that the number of stations so tunable is generally limited makes desirable the possibility of tuning transmitting stations by means of signal seek operation in which the operator by momentarily pressing a bar or button may produce a tuning adjustment from a previously selected station to the next station in order of frequency which produces sufficient signal to produce automatic stoppage of the signal seeking operation the action of which has been initiated.

Signal seek tuning is not, in itself, completely satisfactory since if it is desired to change the tuning from one station to a particular other station it is necessary, in general, to tune through one or more intermediate stations each of which will stop the tuning operation, necessitating multiple operations of the initiating member. This is particularly objectionable in larger metropolitan areas where a large number of transmitting stations will produce strong signals sufiicient to stop the progress of signal seek tuning. Furthermore, signal seek receivers are generally, to'avoid complexity, made to seek in only one direction across the band, and accordingly if a station is desired which lies opposite the direction of the automatic seek it is impossible to reverse the direction of seek, but instead the seek operation must be carried out to one end of the band and thereupon caused to proceed from the opposite end of the band with many stoppages. Additionally, it is sometimes difficult to determine whether the desired station has been selected as, for example, if the tuning is accomplished during a commercial, so that upon each signal seek selection the operator may be required to pause an appreciable time to determine whether or not the tuning has reached the desired station.

The various advantages and disadvantages of the types just mentioned of the several types of tuners have led to proposals to provide combination signal seek and Inasmuch as on occassions the owner of 2,866,095 Patented Dec. 23, 1958 such a tuner, the most desired local stations maybe set up for push button tuning and -the-signal seek operation may then be confined to use in periods when the automobile is outside the range of such local stations. Various proposals have been made for tuners of "this combination type, usually involving the setting up of elements connected with the push buttons which will inhibit signal seek stoppage except'when the tuning'is in the vicinity of desired stations. -In such cases, the manipulation of a push button essentially starts signal seek tuning, but stoppage of the tuning does not 'occur until the desired station frequency is approacehd, whereupon the stoppage inhibiting devices are renderedin'ac- 'tive and signalseek proceeds to the next station "which is presumably the one sought. Such a system, however, involves considerable electrical complexity .and critical adjustment, otherwise the signal seek control will still have arange of frequency bands in which it will assume control with considerable uncertainty as to whether it will effect tuning to the station sought. Attempts t'o secure accuracy involve matters of expense which will take a tuner capable of uniformly certain operation out .of .a commercial price range, as by requiring accurate pretuned circuits, piezo crystals, or the like.

Push button tuners which "have been commercially successful involve mechanical tuning under the control of push buttons to adjust ganged condensers or movable cores of tuning coils. Pre-selecting elements of mechanical type may, in such tuners, be set up and locked and will maintain accurate adjustments indefinitely for the reliable tuning of the selected stations. However, such mechanical push button tuners involve such mechanical loading of the tuning elements which must the adjusted that without the provision of relatively com plex mechanical disconnecting elements there would be required powerful driving means for signal seek purposes which are not only expensive but by virtue of'the power involved give rise to serious accentuation of the trouble which has beset many signal :seek tuners, namely inertial overrun ofheavy rapidly moving parts.

In accordance with the present invention :there is pro vided a combination push button and signal seek tuner, with possibility of manual knob adjustment as well, which overcomes these difficulties permitting, consistently with the highly accurate and dependable push button tuning, the use of a low power, low inertial ,motor which is ideally (adapted for signal seek operation.., A motor of this type and a tuner utilizing the same are described in my application, Serial No. 426,222, filed April .28, I954. The motor referred to is of an inching" type in which the movable element connected to ganged tuning devices is merely a small light rod, the operation of the motor involving the imparting of minute steps of movemnet to the rod which comes to rest after each step. As disclosed in my application, this motor serves to move only a light core assembly associated with coils and consequently the motor is required to deliver only a small amount of power. While the motor could be made more powerful, it is desirable that its power out put ,should be low, and under these conditions it is not well adapted for the adjustment of such mechanism as is desirably provided in a mechanical push button tuner wherein a considerable degree of friction is desirably present to hold the movable parts reliably in a position to which they are adjusted.

.In accordance with the present invention, one of the features contributing largely to the practicability of the combination tuner is the provision of independent ad-.

movements of parts I respectively, push button and signal seek tuning are efof the tuning elements when,

,to, fixed-positions when the coils are adjusted, and, to

maintain, only a limited range of necessary adjustment, when signal seek tuning is'effected the coils should, be brought to predetermined positions. This is accomplished in accordance with the invention.

Foreonsistent operation, various interlocks arev provided in the mechanism, and while these interlocks are Idesirably mechanical, to avoid electrical complexity, they are actuated manually and without necessitating noticeable etfort on the part of the operator. In brief the invention provides a tuner which combines signal seek, :push button and manual knob operation with retention ,or utilization of the best features of all three types.

The broad objects of the invention relate to the at- ,tainment of the foregoing results, and these and numerous subsidiary objects relating to details of construction and operation will become apparent from the following description read 'in conjunction with the accompanying drawing in which:

Figure 1 is a plan view, with parts broken away to show details, of a preferred form of tuner provided in accordance with the invention;

Figure 2 is a vertical section taken on the broken surface indicated at 2-2 in Figure 1;

Figure 3 is a fragmentary elevation showing 'in particular details of a push button assembly;

Figure 4 is a fragmentary plan view showing, in particular, the arrangement of certain elements particularly involved in push button and manual knob operation;

Figure 5 is a similar fragmentary plan view showing certain details of elements illustrated in Figure 4 and certain additional elements;

Figure 6- is a side elevation of the tuner looking at the right of Figure 1;

Figure 7 is a section taken on the broken surface indicated at 77 in Figure 4;

Figure 8 is an enlarged plan view showing details of the signal seek motor and its associated parts;

Figure 9 is a fragmentary section showing a cam and resetting mechanism associated with a manual tuning shaft;

Figure 10 is a section taken on the plan indicated at 10-10 in Figure 9; and

Figure 11 is a diagram showing the electrical connections involved in the tuner and the radio receiver with which it is associated.

As is customary in the case of automobile radios, the tuning unit is generally essentially independent of the major parts of the receiver, though physically arranged for association therewith both structurally and electri- 'cally. The electrical elements of the complete receiver which are located in the tuner are, in the case of a superheterodyne receiver, inductors or condensers which tune the radio frequency amplifiers, the oscillator and mixer. In other types of receivers the elements which are required to be tuned are similarly made parts of the tuner. In what follows, the mechanical elements which are detailed-are those of the tuner alone, the parts constituting the remainder of the complete receiver being structually conventional and diagrammed in Figure 11, these parts being also electrically conventional except for those portions of the circuit having to do with signal seek control.

The tuner comprises a frame, the elements of which generally consist of sheet metal plates associated in converitional fashion and serving for the mounting andguidahce of the operating-parts. For simplicity of showing,

the parts of the frame are largely omitted, it being evident "where parts are required for mounting or guidance' Referring first particularly to Figures 2 and 3, there is shown therein a push button assembly 4 which is largely conventional, there being, for example, five, or more or less, of such push button assemblies depending upon the number of preselected stations to be tuned by push button manipulation. The push button assembly 4 is of the type illustrated and described in Teaf Patent 2,301,090, dated November 3, 1942. This need not be described in detail, but for present purposes may be stated to include a slide member 6 on which is provided at 8 a cam 10 arranged to be lockedin an adjusted position by aclamp lever 12 which is controlled by the stem 14 of a push button 16, the stem being slidable on the slide member 6. When the push button 16 is pulled outwardly relatively to the slide. member 6, the cam 10 'is released for rocking movement. When the push button is forced inwardly relative to the slide member 6 the cam 10 is locked by the lever 12. The slide member 6 is urged forwardly or outwardly by a spring 18 reacting against a plate of the frame 2 through an opening in which the end 20 of the slide member extends.

' The slide members 6 of the several assemblies extend between transverse rods 22 and 24 which are carried by levers 26 and 28 and provide a paddle assembly which is pivoted at 30 and 32 in the frame. This assembly carries an anti-backlash gear segment 34 with which there meshes a pinion 36 secured to a shaft 38 mounted in the frame. The shaft 38 has secured to it a metal disc 40 which is faced with friction material to provide a clutch element cooperating with a crown gear 42 secured to a hub 44 which is journalled upon the shaft 33. The pinion 46 is provided on the inner end of a shaft 45; and is held in mesh with the crown gear 42 by a disc 49 carried by the hub 44. The shaft 48 is guided for horizontal movement in a fixed bracket 51 and is provided with a loose pivot at 53 in the frame. A flexible disc 50 is carried by the shaft 48 and has its periphery pinched between a pair of flexible discs 52 carried by a manual control knob shaft 54 journalled in the frame.

A slide 56 mounted for transverse slidinig movements in the frame and urged toward the right as viewed in Figure 4 by a spring 58 is provided with an end 6% projecting into a groove in the hub 44 for control of the clutching engagement between the disc 40 and the crown gear 42. The slide 56 is provided with a number of fingers corresponding to the push button assemblies each of which has a cam edge 62 engageable by the end 20 of a corresponding push button slide member 6.

The assembly so far described is conventional in commercial tuners and provides for the independent but consistent locating of the assembly comprising the rods 22 and 24 either by push button or manual operation. As will be evident from what has been described, assuming the parts in normal position with the push button slides urged outwardly by spring 18 (outward movements being limited by engagement with the frame in conventional fashions not shown), the clutch provided at 40, $2 is engaged and rotation of knob shaft 54 will serve to effect through the parts described rotation of the assembly comprising the transverse rods 22 and 2 3. This action in the conventional push button tuners serves to adjust cores in tuning coils through connection of the cores to the levers 26 and 28. If a push button is pressed inwardly, its first action is that of camming slide 56 to the left as viewed in Figure 4 through the action of it end 20 on the corresponding cam edge 62, thereby effecting release of the clutch. Further inward movement carries its locked cam member 10 into engagement with one or the other of rods 22 or 24 locating their assembly in a position in which the cam 10 engages both rods and the push button assembly is brought to rest. Thi results in a definite placement of the assembly comprising the rods 32 and 2 4 and according'a definite positioning of the tuning -tion as present by the locked adjustment of the cam 10.

Release of the push button results in its outward movement by its spring 18 with release of the slide 56 to provide reengagement of the clutch 40, 42, leaving the rod assembly in its new adjusted position. The disengag ment of the clutch during push button operation is to relieve the push button of the necessity for driving through the crown gear 42 the shaft 48 and the parts associated therewith out to and including the knob on the shaft 54. Because of the desirable gear reduction which is involved, a drive of the knob by the push buttons would require considerable effort and this is avoided as described.

While on the subject of push button operation, reference will be briefly made to the fashion in which resetting of the cam is effected as described in detail in said Teaf patent. If a push button 16 is pulled outwardly its associated cam 10 is free to rockabout its pivot 8. Adjustment of the tuning knob may then be effected to tune a desired station for which the push button assembly is to be set. When such tuning is accomplished, the push button is moved inwardly causing the cam 10 to engage both of the rods 22 and 24 in their adjusted positions, thereby setting the angular position of the cam. As the push button is forced further inwardly it serves to rock the lever 12 into tight clamping engagement with the cam 10 to retain its set position. Thereafter the cam is effective to produce accurate tuning to the station thus chosen.

In accordance with the present invention, the levers 26 and 28 are not connected to a core assembly but, rather, are connected by links 64 to a carriage 66 which is mounted for forward and backward movement in the frame and carries coils 68, 70 and 72 which constitute the tuning coils of the receiver, these coils, for example, being the tuning coils of the radio frequency amplifier, the oscillator and the mixer of the superheterodyne receiver or the tuning coils of such other type of receiver as may be involved.

The cores of the coils 68, 7 0 and 72 are respectively indicated at 74, 76 and 78 and are adjustably carried by a carriage 80 which is slidable forwardly and rearwardly in guideways 82 forming part of the frame. The longitudinal positions of the cores are adjustable for trimming purposes, and once adjusted, they are rigidly held in the carriage 80.

The carriage 80 is secured to a rod 84 which has an extension 86. A spring 88 reacts between a collar 90 secured to the rod 84- and a fixed abutment 92 on the frame through which the rod 84 extends. The spring 88 accordingly normally urges the rod 84 and its extension 86 toward the rear of the tuner.

The rod 84 comprises the driven element of an inching motor of the type described in my application Serial No. 426,222, filed April 28, 1954. The motor herein shown is fundamentally that of said application but with certain changes in details. The drive is effected through a vibrating armature 94 which is driven as hereafter de scribed. This armature has its end shown in Figures 1 and 8 engageable with a gripping pawl 96 which has an opening through which the rod extension 86 extends. Thi opening is only slightly larger than the rod and has sharp edges effecting a gripping and driving action on the rod. A similar element is provided at 98 to form a gripping detent which prevents movement of the rod under normal conditions under the action of spring 88. A lever 1110 pivoted at 101 to the frame is provided with an ear 12 arranged to the right end of the gripping pawl 96 and with a second ear 10d arranged to engage the right-hand end of the gripping detent 98. The lever 100% also provided with an arched extension 106 which embraces the top of the rod extension 86. Spring 108 is fastened to the extension 106 and to a frame bracket and serves to urge the lever 100 in a counterclockwise direction as viewed in Figures 1 and 8.

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A fixed pin 110 engages one side of therod extension 86. to aid in its accurate guidance and a second fixed pin 114 serves for the same purpose. A fixed pin 112 serves to back up the gripping detent 98, being engaged by the left-hand side thereof as viewed in Figures 1 and 8.

A pair of springs 116 and 118, which may merely be constituted by two ends of a U-shaped spring, respectively engage the forward sides of the right-hand ends of the gripping pawl 96 and the gripping detent 98. The lever 100 is provided with an upstanding pin 120 which is engageable by the hook end 122 of a lever 124 which is urged clockwise as viewed in plan by a spring 125 and is provided with a downturned ear 126 engageable by a pin 128 laterally extending from the rear end of the rod extension 86. A pin 129 on the forward end of the rod extension 86 is arranged for engagement with the end 106 of lever 100.

A ratchet 130 is pivoted to the frame and is arranged to be advanced step by step by a pawl 132 which is pivoted to the end of a lever 134 pivoted at 136 to the frame. A detent 138 engages the ratchet 130 to prevent retrograde movement thereof, a tension spring 140 serving to cause both the pawl 132 and detent 138 to engage the ratchet.

A contact pin 142 carried by the electrically grounded lever 1.00 is arranged to engage an insulated spring contact member 144 when the lever 100 is released by the latch 124. The arrangement of the switch thu provided in the electrical circuit will be described later.

The latch 124 is arranged to be disengaged from pin 120 under the action of a lip 146 formed on a bracket 148 which is carried by a slide 150 guided in the frame for transverse movements and located below the slide 56. A spring 151 urges this slide 150 toward the left. The slide is provided with cam edges 152 which are respectively engageable by the rear ends of the push button slides 6 to move the slide 150 towards the right against the action of spring 151.

A turned end 154 on the slide 150 is arranged to engage the push button 156 of a microswitch 158 the location of which in the electrical circuit will be later described.

At its right-hand end the slide 150 is connected by link 160 to the rear end of a lever 162 which is mounted for pivotal movement loosely upon posts 163 by studs 164 and 166.

The manual drive shaft 48 has secured thereto a collar 168 which is provided with a friction facing 170 engageable by the face of a cam disc 172. The disc 172 is provided with a concave camming edge 174 which is arranged to act upon the forward end 176 of the lever 162. At the ends of the camming edge 174 there are provided ledges 178 beyond which are located radially extending stops 180. A spring 182 reacts between flexible driven disc 50 and the face of the disc 172 to force the latter into engagement with the facing 170 to provide a clutching action whereby the rotation of the shaft 48 will rotate the disc 172 to cam toward the left the lever end 176. When a limit of motion is reached, however, slippage may occur between the face 170 and the disc 172.

Secured to the front of the disc 172 is a semicircular member 184 which provides a pair of radially located abutment ends 186. The member 184 is flanged at 188 to provide between the flange and the front of the disc 172 a guide space for a yoke 190 which is provided with shoulders 192 engageable with the abutments 186, and has depending legs 194 which are pivoted to a block 196 secured to a transverse shaft 198 having bearings at its ends in the frame.

At its ends the shaft 198 has secured to it a pair of upright arms 200. Pivoted to the left and right-hand portions of the frame 202 are levers 204. To each arm 200 and its associated lever 204 where is pivoted a link 206. providing an approximate parallelogram linkage. The forward ends of the links 206 are connected together by 2' a bar 208 which is arranged to be engaged by an operator to rock the shaft 198 and initiate signal seek operation.

' Pivoted to a forwardly extending arm 210 forming a part of lever 204 is a link 212 the rear end of which is pivoted in a hole in the right-hand end of lever 134. When the bar 208 is in its normal forward position, the arm 210 is approximately in dead center position with respect to link 212. The lever 134 is provided with a downwardly turned extension 214 which is arranged to engage the push button 216 of a single-pole double-throw switch 218 the location of which in the electrical circuit will be described hereafter.

The shaft 198 has secured thereto a depending arm 220 to which is pivoted a link 222 guided for sliding movements in the frame. The link 222 is provided with an car 224 extending upwardly and arranged to engage the upper rod 22 of the paddle assembly. An extension 226 of link 222 is connected to a tension spring 228 anchored to the frame and serving to urge the shaft 1% in a counterclockwise direction as viewed in Figures 6 and 7. The link extension 226 is provided with a notch 230 in which, in the normal rest position of the parts, there lies a roller 232 carried by a strap 234 secured to the slide 56. The arrangement is such that, when the link 222 is moved forwardly by clockwise rocking of the shaft 198, the roller 232 is forced toward the left by the rear portion of the notch thereby causing the slide 56 to be moved toward the left.

Reference may now be made to the wiring diagram, Figure 11. It will be evident that the tuner involved herein may be applied to many forms of radio receivers, and consequently the type of receiver indicated is illustrated only by way of example. The receiver illustrated is of the presently conventional superheterodyne broadcast receiving type for amplitude modulated signals, but the tuner is adapted equally for the tuning of receivers for frequency modulated signals, receivers capable of receiving both amplitude and frequency modulated signals, ultra high frequency receivers, or others. In general it is adapted for varying the tuning elements of any receiver which is capable of providing, in its own suitable fashion, a signal seek controlling output. Aiming the description specifically at the superheterodyne receiver illustrated, this comprises conventional radio frequency amplifier stage t 250, a converter 252 embodying a local oscillator, an intermediate frequency amplifier 254, the final tube of which is indicated, the coupling transformer 256, a diode detector which forms part of a tube 258 which also provides a first audio amplifier stage, an audio amplifier 264, and f a loud speaker 266. All of these elements may take conventional forms and, of course, either or both of the amplifiers 250 or 264 might be omitted depending upon the characteristics of operation desired. The coils 68, 70 and 72 constitute tuning elements of the radio frequency, oscillator, and mixer stages. If the receiver was of a different type, one or more of these coils would be used as a tuning element thereof. Desirably the volume control is provided in the diode network 260 in the form of a manually adjustable potentiometer 262.

As shown in the diagram, there is connected at 267 to the primary of the transformer 256 the input terminal of a conventional balanced discriminator 268 which embodies the diodes 270 and 272 and which is so adjusted, in conventional fashion, as to provide at its output terminal 274, a potential, which, as tuning proceeds in the direction of scanning, provides a D. C. signal derived from the intermediate frequency amplifier, which first increases negatively to a peak value, then decreases in amplitude through a zero value, and thereafter increases to a positive peak value, later decreasing as tuning continues. This action occurs in conventional fashion since the intermediate frequency signal arising from tuning varies in frequency, the discriminator being of the type commonly used for the detection offrequency modulated signals.-

The output terminal 274 of the discriminator is connected through resistor 276 to the control grid of a thyratron 278, there being provided between the control grid and ground the capacitor 280. The switch provided by the pin 142 and spring blade 144 is connected between the control grid and ground as diagrammed.

The cathode of the thyratron 278 is connected to the adjustable contact of a potentiometer 284 in series with Which there is a resistor 282 and the switch 158 previously mentioned.

To the left-hand end of the resistance of potentiometer 284- as diagrammed there is connected one terminal of the D. C. actuating coil 286 of the motor 288 which embodies the vibrating member 94 previously mentioned. T his motor also includes an alternating current winding which is energized from terminals 292 connected to the source of alternating current in the conventional automobile power supply system, which usually involves a vibrating type of converter drawing direct current from the automobile battery and generator, converting it into high voltage alternating current and then providing recti fication to supply the direct B voltage for the receiver. The terminals 292 may be connected either to a high or low voltage portion of the A. C. circuit of the power supply, the coil 291) being wound to correspond thereto.

The left-hand end of the coil 286 is connected to one terminal of the winding 294 of a relay, the other terminal of which is connected through resistor 296 to the movable member of the switch 218 which normally engages contact 298 connected at 386) to the anode of thyratron 278. When the actuating plunger 216 is moved by the portion 214 of lever 134 the switch 218 engages contact 3492 which is connected at 304 to one end of a resistor 386, the other end of which is connected to the 3+ terminal 308. (Other connections from this positive supply terminal to the receiver are conventional and not indicated.) The connection 304 also runs to the movable relay element 310 which, when the relay is energized, engages contact 312 which is connected to the right-hand end of the resistor 22%. A second movable member 314 of the relay is connected through line 315 to the connection 267 between the primary of transformer 256 and the discriminator 268. When the relay coil 294 is deenergized the member 314 engages contact 316 which is connected at 318 to the positive supply terminal 308 and at 320 to the input terminal of the discriminator which is remote from connection 267. When the relay coil 294 is energized, the member 314 engages terminal 322 which is connected at 324 to the anode-connected terminal of the primary of transformer 256.

The circuit which has been described is generally similar to that disclosed and claimed in the application of Donald L. Birx, Serial No. 426,237, filed April 28, 1954, and disclosed also in my application Serial No. 426,222, filed April 28, 1954. The latter application discloses and claims a motor essentially simliar to the one herein shown, and reference may be made to either of said applications for various details of operation of both the circuit and motor.

The operation of the tuner may now be described.

The various figures of the drawings show the parts of the tuner consistently in the positions which are occupied under conditions of tuning, under signal seek action, of a station.

Under these conditions, considering first the electrical circuit, the discriminator 268 will have previously imposed a potential on the control grid of thyratron 278 which will have resulted in firing thereof. However, following firing the thyratron will have become extinguished due to removal of positive potential from its anode. The firing of the thyratron 278 will have deenergized relay coil 294 with the result that members 311 and 314 occupy their lower positions. The latter engages contact 316 and as will be noted from tracing the circuit connections this will have effected short-circuiting of the input to the discriminator so that the connection 267 will be directly connected to the positive supply terminal 308. The result is that the passage of signals through the transformer 256 is the same as if the discriminator was not present and without attenuation due thereto.

The D. C. coil 286 of the motor is deenergized and consequently the armature 4 is stationary despite the continued flow of alternating current through winding 290. The bar 86 will be held by the gripping detent 98 in the position previously attained. The lever 100 will be latched in its clockwise position by the detent 124. The switch provided at 142, 144, will be open. The cores 74, 76 and 78 will be located as determined by the positions of the rod 86, and. the coils 68, 70 and 72 will occupy their extreme forward positions as imposed by the previous action of the ear 224 of the link 222. Clutch 40, 42 is engaged by reason of the right-hand position of slide 56, and slide 150 will occupy its extreme left-hand position, permitting switch 158 to remain closed. The normal conditions of the other elements will be obvious or made clear from the following description.

Let it be assumed that with these conditions pre-existing, that it is desired to tune the receiver manually by rotation of the knob shaft 54. The initial rotation of this shaft effects rotation of shaft 48 with the result that cam disc 172 is frictionally rotated and, through its camming action, will rock toward the left end 176 of lever 162, there being finally brought to engagement with this leverone or the other of the ledges 178 depending upon the direction of rotation of the knob. As the knob continues to rotate one or the other of the ears 180 will prevent further rotation of the cam disc 172 and slippage will occur betweenit and the facing 170.

The rocking of lever 162 will cause its rear end to movejtoward the right pulling, through link 160, the slide. 150to the right. This effects several actions as follows:

Switch 158 is opened, but this will produce no results unless the knob is turned while the seeking action is still continuing. In the latter case it will open the circuit including the motor winding 286 and the relay coil 294, putting the electrical circuit in the condition already described.

The movement of slide 150 to the right will cause lip 146 to move the latch 124, releasing the pin 120 and permitting lever 1th) to move counterclockwise under the action of spring 168. This movement of the lever 100 causes ears 102 and 104 to press forwardly upon the members 96 and 98 to release the rod '86 which will then be driven rearwardly by its spring 88 to position the cores 74, 76, and '78 in their rearmost positions. At the end of the stroke of the rod 86, pin 129will strike the extension 106 of lever 100 and restore it momentarily to its clockwise position, but since latch 124 will still be held disengaged, and since spring 88 is weaker than spring hi8, the lever 100 will finally remain in its counterclockwise position. In this counterclockwise position the lever 100 will close the switch at 142, 144, but in the operation under discussion this action will have no eifect.

The continued rotation of the knob shaft 54 will then effect tuning by movement of the coils 68, 70 and 72 relatively to their stationary cores. These cores will have been positioned, as described, in initial positions which are their rearmost positions, so that a full range of movement is vimpartable to the coils to tune over the entire tuning range. The result is free mechanical tuning independent of the signal seek elements, and also independent of the push button tuning elements, the latter independence being obvious from the mechanism.

There may be next considered push button tuning starting from the same initial conditions previously mentioned as-resulting from a completion of a signal seek operation. As a push button, the cam of which has Iii been previously positioned and locked tocorrespond to a particular station, is pushed rearwardly, the end of its slide 6 will effect movements of both slides 150 and 56. The movement imparted to slide 150 produces the same results as those already described in connection with the movement of this slide by manual knob tuning, and these operations need not, therefore, be redescribed, the ultimateeffect again being to restore the cores 74, 76 and 78-to their initial rearmost positions. The slide 56 moves toward the left and this results in release of the clutch provided by the members 40 and 42. The paddle assembly is thus free to rotate without enforcing rotation of the crown gear 42, shaft 48, and their associated parts. As the push button is moved further inwardly to its arrested position, its cam engages, in the usual fashion, one or the other of rods 22 and 24 aligning them at the angle of its cam 10 and thereby positioning the coils 68, 70 and 72 in the positions tuning the receiver to the desired station. Release of the push button leaves the coils in-the tuned position, and, while the slides 56 and 150 are released, the only resulting action is that of producing reengagement of the clutch elements 40 and 42 which will serve to hold the coils in tuned position by reason of the gear ratio involved at 42 and 46 and the normal friction of the parts connected to pinion 46.

It will be now evident that following either manual or push button operation the parts occupy the same positions as originally described with the exception that, depending upon whether manual knob tuning has been effected, the cam disc 172 may be displaced from its normal position illustrated in Figure 9, and that latch 124 does not hold lever in its clockwise position, this lever remaining in its counterclockwise position. It may be noted that if push button operation had followed manual knob tuning, without the interposition of signal seek the slide 150'may be continuouslyheld in its right-hand position by reason of the cam disc displacement which resulted from manual knob tuning.

If signal seek operation is now attempted, the following sequence of operations occurs:

Signal seek operation is initiated by rearward movement of the bar 208 followed by its release. As the bar 208 is moved rearwardly, one of the actions which occurs accompanying clockwise rotation of shaft 198, as viewed in Figures 6 and 7, is a downward movement of element 196 which pulls downwardly the yoke 190. Referring to Figure 9, it will be evident that this causes engagement of one or the other of shoulders 192 with the corresponding abutment 186 of member 184, producing a rocking of the cam; disc 172to its normal position illustrated in Figure 9, wherein the end 176 of lever 162 is released. This permits movement of slide 150 toward the left permitting closure of switch 158 and moving lip 146 to release the latch 124 which is thus located in position to engage the pin Another action which occurs upon rearward movement of the bar 208 and attending clockwise movement of the shaft 198 is the forward movement of link 222 and its extension 226. As the link moves forwardly, the roller 232 is cammed out of the notch 230 moving the slide 56 toward the left and releasing the clutching engagement between disc 40 and crown gear 42, thus releasing the paddle assembly from restraint on its motion. This action occurs substantially immediately upon initiation of the motion of the link 222 which, in moving further forwardly, produces engagement of its car 224 with the upper paddle rod 22 to restore the coils 68, 70 and 72 to their extreme forward positions.

The same rearward movement of the bar 208 moves the link 212 rearwardly. Due to the initial approximate dead center position of arm 219, this movement of link 21.2 lags the other operations discussed above. Movement of link 212 results in counterclockwise movement of the lever 134 producing an advancement, by one tooth, of the ratchet under the action of its driving pawl. In the event that lever 100. should not at this time occupy its clockwise position, as will be the case if knob or push button tuning preceded the operation of bar 208, its follower 103 will be cammed by a tooth of the ratchet to this clockwise position, whereupon the latch 124 will hold it therein. The advance of the ratchet causes the tooth to clear the follower 103, so that the follower is free subsequently to drop into a space between the ratchet teeth. It may be noted that this clearance of follower 103 by the ratchet teeth permits lever 100 to move counterclockwise even if bar 208 is held in its rearmost position.

Another action of the rocking of lever 134 .is movement of the switch arm 218 into engagement with contact 302, whereupon various electrical conditions are set up as will become apparent from consideration of Figure 11. The closure of this switch is at the extreme end of movement of the shaft 198 and this insures that a full stroke is given to bar 208, otherwise the signal seek action will not be initiated.

Engagement of contact 302 provides a closed circuit from positive supply terminal 308 through resistor 306, connection 304, switch 218, resistor 296, relay coil 294, motor winding 286, potentiometer 284, resistor 282, and closed switch 158. The energizing of relay coil 294 causes member 310 to engage contact 312 and also causes member 314 to disengage contact 316 and engage contact 322.

As will be evident from the diagram, the circuit closure at 310, 312 provides a circuit in parallel with that closed at 218, 302, thereby providing a holding circuit maintaining relay coil 294 and the Winding 286 energized.

The closure of the circuit at 314, 322 short circuits the primary of transformer 256, thus muting the loud speaker by interrupting the progress of signals through the detector and audio frequency amplifier stages. At the same time a maximum signal is applied from the intermediate frequency amplifier to the discriminator 268 without attenuation due to the primary circuit of the transformer 256.

Release of the bar 208 effects attainment of the alternative position of the switch 218 with resulting contact at 298 and, through connection 300, the application of positive potential to the anode of thyratron 278.

The release of bar 208 also retracts the pawl 132 to position for its next active stroke, the detent 138 holding the ratchet against retrograde movement.

The link 222 moves rearwardly under the action of spring 228, which restores the shaft 198 to its initial counterclockwise position thereby releasing the rod 22. At the end of the rearward motion of link 222 the notch 230 is brought into alignment with roller 234 so that the slide 56 may again move to the right effecting clutching at 40, 42 thereby frictionally holding the paddle assembly and the coils 68, 70 and 72 in fixed position.

Operation of the motor 288 now takes place as described in my prior application, with vibration of the armature 94 due to the polarized condition imposed by the direct current through winding 286 and the alternating field existing in the gap in which the armature moves. Vibration of the armature imparts movements to the gripping member 96 and the rod 86 is advanced forwardly against the action of spring 88 to move the cores 74, 76 and 78 outwardly of their respective coils. Retrograde movements of the rod 86 are prevented by the gripping detent 98. Both of the members 96 and 98 are operative under the action of springs 116 and 118, being released by the ears 102 and 104.

The tuning action thus initiated continues, and as there is approached tuning to a station of sufficient signal intensity at the receiver the potential at 274 first goes negatively and then positively, passing through zero as the station is tuned. The cathode of the thyratron 278 has its potential adjusted positively above ground by the adjustment of the contact of the potentiometer 284, and this adjustment may be varied to predetermine the signal strength required for stoppage of the signal seek action.

As described in greater detail in said Birx application, depending upon the initial adjustments of the discriminator circuit the thyratron is fired by the rise of its control grid potential upon the attainment of accurate tuning. This, depending upon adjustment, may occur upon attainment of a predetermined positive potential applied to the control grid. Desirably, adjustments are such that if the thyratron control grid is at ground potential the thyratron will be in non-firing condition. A potential of the control grid above ground (though negative with respect to the cathode) is required for firing.

When the thyratron fires the following actions occur: It will be noted that the thyratron has a circuit to ground which to the extent of the right-hand portion of potentiometer 284 and resistor 282 is common with the circuit through the relay 294 and winding 286. When the thyratron fires, its anode to cathode potential drop is low with the result that the potential of the contact of poentiometer 284 is raised so as to differ from the potential existing at the right-hand end of resistor 296 by only a relatively few volts. The result is that insufficient current will pass through the winding 286 to maintain operation of the motor and insufficient current will pass through the winding 294 to maintain it effectively energized with the result that the switch arms 310 and 314 will be pulled downwardly by their actuating spring as viewed in Figure 11, opening the contacts at 312 and 322 and closing the contact at 316. As a result, the relay 294 and winding 286 are completely deenergized, and simultaneously positive potential is removed from the anode of thyratron 278. It may be noted that the motor stoppage is due directly to the firing of the thyratron and is not dependent upon rapidity of action of the relay. Thus, the relay need not be of a quick break type and need only be such as required to provide a holdingcircuit permitting momentary operation of bar 208 and to provide for switching of the discriminator. The result of the foregoing is substantially immediate stoppage of the rod 86 with holding of the cores 74, 76 and 78 in their adjusted position tuning in the signal of the station which occasioned the stoppage. The contact between member 314 and 316 now short circuits the input to the discriminator, while the primary of transformer 256 is restored into the circuit by removal of its short circuiting connection, with the result that the transformer 256 passes signals without attenuation by the discriminator. Accordingly, normal operation of the receiver results.

It may be noted that the circuit is such that even if the signals from the received station are interrupted, as by the passage of the automobile through a steel enclosed bridge or tunnel or the like, there is not initiated any signal seeking action, the receiver remaining tuned in the condition attained.

When it is desired to seek the next station, the bar 208 is again moved rearwardly. The mechanical actions referred to previously occur but are not effective except for the closure of the circuit at switch 218 and contact 302. This results in a restoration of the signal seek condition of the electrical circuits, and operation proceeds as before until the next station is tuned in.

If the signal seek operations are repeated, there will eventually be reached the condition of limit of motion of the rod 86 whereupon the pin 128 will engage the extension 126 of the detent 124 which disengages the pin 120 and releases the lever for forward movement under the action of spring 108. (It may be noted that this may occur even if the bar 208 is held rearwardly due to clearance of follower 103 by teeth of ratchet wheel 130.) When this occurs, the restraining actions of the gripping members 96 and 98 are destroyed with the result that the bar 86 is moved sharply rearwardly under the action of spring 88 to move the cores 74, 76 and 78 to their rearmost starting positions. During such movement, it is desirable that the signal seek action should not take place and accordingly there is the provision of the switching contact at 142 and 144 which is closed grounding the control grid of the thyratron 278 so that it will not be fired when during the return stroke of rod 86 the tuning elements pass through positions tuning in successive stations.

When the rod 86 reaches its extreme rearward position, the pin 129 strikes the extension 106 of lever 100 moving it rea'rwardly so that lever 100 will be latched by I the action of latch 124. When this occurs, contact between 142 and 144 is opened, and the circuit conditions are restored for signal seeking operation. The motor 94, accordingly, again 'advances'the rod 86 until tuning of a station occurs providing a signal firing the thyratron 278, again effecting stoppage in a tuned condition.

It may be noted that if the signal seek bar 208 is held rearwardly the signal seek action will continue indefinitely, interruption occurring only after the signal seek bar is released and a station is thereafter tuned in.

From the foregoing description it will be evident that there is provided in accordance with the invention a tuner which embodies manual knob operation, push button operation, and signal seek operation without conflict with each other and with proper transition between the various modes of operation. The result is a tuner which, as discussed in the beginning of this description, is highly satisfactory in operation, the tuner providing accurate mechanical push button tuning for a group of stations for which the push button assemblies are preset, while providing signal seek operation under conditions out of the ranges of such preset stations or when it is desired, even within their ranges, to provide signal seek of other stations. At the same time the tuner is always ready for manual tuning if that is desired.

One of the important aspects of the invention has to do with the independent movements of the coils and cores for tuning operations. During manual or push button operation, the cores are in definite fixed positions and the coils are moved. On the other hand during signal seek operation the coils are fixed in definite positions while tuning takes place through movements of the cores. It will be evident that the system described is also applicable to the tuning of condensers, in which case both the usually movable and the usually fixed plates may both be made movable, one set during push button and knob tuning and the other during signal seek tuning. It will also be evident that many details, both mechanical and electrical may be changed without departing from the invention; for example, other push button systems may be used as are known in the art and other signal seek controls of known types may also be used. In fact, even an inertialess signal seek control may be used involving the control of core reluctance by direct current, in which case the push button and/or knob mechanical tuning mechanism may move either cores or coils and the signal seek action may depend only upon the variation of reluctance due to controlled current, the interlocks being provided in obvious fashion.

What is claimed is:

l. A tuner for a signal receiver comprising variable impedance tuning means, said variable impedance tuning means including a pair of relatively movable elements, push button operated means for moving one of said elements to effect tuning, and signal seek means, of the type having its signal seeking operation manually initiated and stopped in response to the tuning of a signal, for moving the other of said elements to effect tuning.

2. A tuner for a signal receiver comprising variable impedance tuning means, said variable impedance tuning means including a pair of relatively movable elements, means for moving one of said elements to effect tuning, signal seek means, of the type having its signal seeking operation manually initiated and stopped in response to the tuning of a signal, for moving the other of said 1 4 elementsto effect tuning, and means forlocating said first mentioned movable element in a predetermined position upon initiation of signal seeking operation.

3. A tuner for a signal receiver comprising variable impedance tuning means, said variable impedance tuning means including a pair of relatively movable elements, push button operated means for moving one of said elements to efiect tuning, signal seek means, of the type having its signal seeking operation manually initiated and stopped in response to the tuning of a signal, for moving the other of said elements to effect tuning, and means for locating said first mentioned movable element in a predetermined position upon initiation of signal seeking operation.

4'. A tuner for a signal receiver comprising variable impedance tuning means, said variable impedance tuning means including a pair of relatively movable elements, means for moving one of said elements to elfect tuning, signal seek means, of the type having its signal seeking operation manually initiated and stopped in response to the tuning of a signal, for moving the other of said elements to effect tuning, and means for locating said other element in a predetermined position upon operation of said means for moving the first-mentioned element.

5. A tuner for a signal receiver comprising variable impedance tuning, means, said variable impedance tuning means including a pair of relatively movable elements, push button operated means for moving one of said elements to effect tuning, signal seek means, of the type having its signal seeking operation manually initiated and stopped in response to the tuning of a signal, for moving the other of said elements to effect tuning, and means for locating said other element in a predetermined position upon push button operation.

6. A tuner for a signal receiver comprising variable impedance tuning means, said variable impedance tuning means including a pair of relatively movable elements, means for moving one of said elements to effect tuning, signal seek means, ofthe type having its signal seeking operation manually initiated and stopped in response to the tuning of a signal, for moving the other of said elements to effect tuning, means for locating said first mentioned movable element in a predetermined position upon initiation of signal seeking operation, and means for locating said other element in a predetermined position upon operation of said means for moving the first mentioned element.

7. A tuner for a signal receiver comprising variable impedance tuning means, said variable impedance tuning means including a pair of relatively movable elements, push button operated means for moving one of said elements to effect tuning signal seek means, of the type having its signal seeking operation manually initiated and stopped in response to the tuning of a signal, for moving the other of said elements to effect tuning, means for locating said first mentioned movable element in a predetermined position upon initiation of signal seeking operation, and means for locating said other element in a predetermined position upon push button operation.

8. A tuner for a signal receiver comprising variable impedance tuning means, said variable impedance tuning means including a pair of relatively movable elements, means for moving one of said elements to effect tuning, signal seek means, of the type having its signal seeking operation manually initiated and stopped in response to the tuning of a signal, for moving the other of said elements to effect tuning, said signal seek means including an inching type motor having a member electrically driven in one direction for seeking action and a spring acting on said member to restore it and said other of said elements to an initial position, and means for releasing said member for action by said spring to locate said other element in its initial position upon operation of said means for moving the first mentioned element.

9. A tuner for a signal receiver comprising variable impedance tuning means, said variable impedance tuning means including a pair of relatively movable elements, means for moving one of said elements to effect tuning, signal seek means, of the type having its signal seeking operation manually initiated and stopped in response to the tuning of a signal, for moving the other of said ele ments to effect tuning, said signal seek means including an inching type motor having a member electrically driven in one direction for seeking action and a spring acting on said member to restore it and said other of said elements to an initial position, means for releasing said member for action by said spring to locate said other element in its initial position upon operation of said means for moving the first mentioned element, and means for locating said first mentioned movable element in a predetermined position upon initiation of signal seeking operation.

10. A tuner for a signal receiver comprising variable impedance tuning means, said variable impedance tuning means including a pair of relatively movable elements, means for moving one of said elements to effect tuning, signal seek means, of the type having its signal seeking operation manually initiated and stopped in response to the tuning of a signal, for effecting tuning of said variable impedance tuning means independently of movement of said one of said movable elements, means for locating said one of said movable elements in a predetermined position upon initiation of signal seeking operation, and means for effecting a predetermined tuning condition of said variable impedance in the last mentioned fashion upon operation of said means for moving said one of said movable elements.

11. A tuner for a signal receiver comprising variable impedance tuning means, said variable impedance tuning means including a pair of relatively movable elements, push button operated means for moving one of said elements to effect tuning, signal seek means, of the type having its signal seeking operation manually initiated and stopped in response to the tuning of a signal, for effecting tuning of said variable impedance tuning means independently of movement of said one of said movable elements, means for locating said one of said movable elements in a predetermined position upon initiation of signal seeking operation, and means for effecting a predetermined tuning condition of said variable impedance in the last mentioned fashion upon push button operation.

12. A tuner for a signal receiver comprising variable impedance tuning means, said variable impedance tuning means including an impedance constituted by a pair of relatively movable elements, the value of said impedance being substantially solely dependent upon the relative positions of said elements, means for moving one of said elements to effect tuning, and signal seek means, of the type having its signal seeking operation manually. initiated and stopped in response to the tuning of a signal, for moving the other of said elements to effect tuning.

References Cited in the file of this patent UNITED STATES PATENTS 2,394,869 Nicholson Feb. 12, 1946 2,402,260 Sands June 18, 1946 2,499,573 Dunn Mar. 7, 1950 2,501,003 Pifer Mar. 21, 1950 2,512,714 Carlzen June 27, 1950 2,744,193 Schwarz May 1, 1956 

